One big difference is that the last hole in the last photo needs to be added to the felt for the MKIII but not the MKII. The MKIII has a very poor low end response if you cover the opening on the back of the driver from what I've seen. Another difference is that I use soft felt for the back of the MKII driver and stiff felt for the back of the MKIII driver. The mod photos, except for the last one are for the MKII steps.

The reason I placed the holes in that pattern is that they align perfectly with the outer grids of the driver. It seemed proper to have sound travel through uniform channels as to keep the sound as clean and controlled as can be. I was very happy with the sound in all the mods I've made so far.

In on the two YouTube videos, people punched holes randomly in the felt. They made it appear as if the number was more important than the placement. Holes randomly punched in a dampening medium and what I know about acoustics didn't seem to mesh.

I spent a couple of days reading and and this was what I decided to do. I based it off certain parts of incremental mods that I read about, the parts included in the Mayflower mod kit, two different YouTube videos, many years of acoustic experience, and SWAG (Scientific Wild Ass Guessing). I was pretty happy with the results and all my other audiophile friends were amazed by them.

I even reached out to Dan Clark who is located pretty close to me about making another set for me, but he plainly refused. That was it, if I wanted modded Fostex I would need to build them myself (I didn't know of any other at the time than MrSpeakers).

This whole modding thing started when I decided I needed some audiophile headphones and I am cheap. I found by reading that headphones can easily be modded for superior sound, Fostex T50RP are some of the most popular headphones to mod, planar > dynamic, and MrSpeakers discontinues the Mad Dog.